1. Field of the Invention
The present invention is a filler tube assembly for communicating fuel from a fuel pump nozzle to a fuel tank with the fuel pump nozzle having a pressure sensing port.
2. Description of the Related Art
Fuel overflow during the fueling of boats is common and results in fuel contamination of lakes, rivers, and other waterways. Federal law prohibits spilling fuel into a lake, river, or waterway, and penalties for violating such laws may be severe. Such fuel overflow has been reduced by advancements in fuel pump nozzles, but such advancements have not eliminated overflow and the resulting pollution of waterways.
Boats generally include a fuel tank and a filler tube assembly extending from a surface of the boat to the fuel tank. The filler tube assembly includes a receiver that receives a fuel pump nozzle. Standard fuel pump nozzles generally have an automatic shut-off system. When activated, the automatic shut-off system discontinues the flow of fuel through the fuel pump nozzle. Specifically, the automatic shut-off system responds to a pressure change at the pressure sensing port. The fuel pump nozzle draws a vacuum through the pressure sensing port and when the pressure sensing port is covered, e.g., with fuel, the automatic shut-off system senses the change in pressure and discontinues the flow of fuel through the fuel pump nozzle.
Generally, as the fuel tank is filled with fuel, the fuel level rises to the top of the tank, into the filler tube assembly, and into the receiver. When the fuel level covers the pressure sensing port on the fuel pump nozzle, the pressure sensing port senses a pressure change which activates the automatic shut-off system on the fuel pump nozzle. Fuel flow is thereby terminated, thus preventing fuel overspill from the fuel fill neck.
Fuel tanks on boats typically include a vent tube to dissipate pressure increases in the fuel tank and to prevent vacuum when an engine is drawing fuel from the fuel tank. The vent tube is generally in the form of a tube connecting from the fuel tank to a side of the boat, thereby allowing the fuel tank to remain at atmospheric pressure. In today's boats, the height of the vent tube may be below the height of the receiver fitting. Therefore, as the fuel tank is filled, and as the fuel level rises to the top of the fuel tank into the filler tube assembly, fuel also rises at a corresponding level in the vent tube. If the height of the vent tube on the side of the boat is lower than the receiver, and hence lower than the pressure sensing port, fuel evacuates through the vent tube and onto the waterway surface before the fuel flow is terminated by the automatic shut-off system on the fuel pump nozzle.
Fuel overflow also occurs when, upon filling the tank, the tank belches, thereby expelling some fuel back through the receiver fitting. Belching is generally caused by turbulent flow in the fuel fill neck. Belching may also be caused by air that is trapped with the fuel as the fuel enters the fuel fill neck. As a result the backpressure created by the air restricts or eliminates fuel flow, generally at which point the fill neck belches, or releases, the air through the receiver fitting, which may result in fuel splashing out of the receiver fitting.
In addition, underground fuel reservoirs are generally at a temperature substantially cooler than the temperature of the boat's fuel tank and the fuel undergoes thermal expansion after it is pumped from the cool reservoir to the warm fuel tank. Generally expansion continues after the fuel tank is filled and the fuel fill receiver is capped, resulting in excess fuel being expelled through the vent tube and onto the waterway surface.
Accordingly, it would be desirable to manufacture a filler tube assembly that activates the automatic shut-off system on the fuel pump nozzle when the fuel reaches a predetermined level to prevent leakage of fuel through the vent tube and to leave excess volume to accommodate for thermal expansion of fuel.